Wireless datagram transaction protocol system

ABSTRACT

Systems are provided for sequencing, delivery acknowledgement, and throttling of data packets over a network layer, such as UDP and SMS. To support devices with limited battery resources, the invention incorporates asymmetric retry logic and/or acknowledgements with overlapping ranges, to minimize the transmissions required for the device. The sender of a data-bearing frame does not need to wait for a frame to be acknowledged before sending the next, such that many frames can be “in flight” at once.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.13/273,593, filed Oct. 14, 2011, which is a continuation of U.S.application Ser. No. 12/776,316, filed May 7, 2010, which is now issuedas U.S. Pat. No. 8,059,654, which is a division of U.S. application Ser.No. 11/218,077, filed Aug. 31, 2005, which is now issued as U.S. Pat.No. 7,746,787, which is a continuation of U.S. application Ser. No.10/371,335, filed Feb. 14, 2003, which is now issued as U.S. Pat. No.6,965,564. Each of the aforementioned patent(s) and application(s) arehereby incorporated by reference in their entirety.

This application is also related to PCT Application No. PCT/US04/04526,entitled Wireless Datagram Transaction Protocol System, filed 12 Feb.2004, which claims priority to U.S. application Ser. No. 10/371,335,entitled Wireless Datagram Transaction Protocol System, filed 14 Feb.2003, issued as U.S. Pat. No. 6,965,564 on 15 Nov. 2005.

FIELD OF THE INVENTION

The invention relates to the field of wireless connections between awireless device and a network. More particularly, the invention relatesto wireless datagram protocol processes and structures between awireless device and a server.

BACKGROUND OF THE INVENTION

In local area networks, such as wireless home networks, one or morewireless devices, e.g. such as IEEE 802.11b devices, are typicallylinked to the network through a server or network access point. Wirelesssignals link the wireless devices to the server, through forward linkand reverse link fading signals. Information to be communicated isorganized within streams of packets and datagrams, which are sent incompliance with a communications protocol. While packets and datagramsare controllably sent from a sender to a receiver, some of the packetsand datagrams can be lost during transmission, due to wireless signalfading. While communications protocols between wireless devices andservers typically provide means to acknowledge receipt of data and meansto request a retransmission of missing data, the acknowledgement andretransmission of data requires a great deal of power expenditure forwireless devices.

P. Soni and A. Chockalingam; Performance Analysis of UDP with EnergyEfficient Link Layer on Markov Fading Channels; Wireless Research Lab,Department of Electrical Communication Engineering, Indian Institute ofScience, Bangalore, India, describe “an analysis of the throughput andenergy efficiency performance of user datagram protocol (UDP) usinglinear binary exponential and geometric backoff algorithms at the linklayer (LL).”

Christine E. Jones, Krishna M. Sivalingam, Prathima Agrawal, Jyh-ChengChen, A Survey of Energy Efficient Network Protocols for WirelessNetworks, School of EECS, Washington State University, Pullman Wash.,January 2000; describe that the “network interface of wireless networksis a significant user of power, and that research has been devoted tolow-power design of the entire network protocol stack of wirelessnetworks in an effort to enhance energy efficiency, and describes recentwork addressing energy efficient and low-power design within all layersof the wireless network protocol stack.”

T. Laporta, F. Sabnani, and T. Woo, Two-Way Wireless Messaging SystemWith Transaction Server, U.S. Pat. No. 6,014,429, describe “a two-waywireless messaging system, which has a messaging network, and a two-waymessaging device that originates, receives and replies to messageshaving dynamic message components to and from the messaging network. Atransaction server is located within the messaging network for openingand tracking messages among various users of the two-way messagingsystem, and closing a transaction to prevent further message deliveryand replies after a predetermined transaction is completed. Atransaction can remain open until a reply has been received by everyintended message recipient; until a desired number of message recipientreceived a message; or until a specified amount of time has expired.”

W. Thielke, B. Fridman, and V. Shimarov, Optimized WirelessCommunication System, U.S. Pat. No. 6,324,564 B1, describe “an optimizedwireless communication system which includes an enhanced communicationstransport protocol to reduce the overhead required by the system andintelligent protocol agents (IPAs) that process and optimize standardapplications before passing them on to the transport protocol.”

Other publications provide various details of the operation of wirelessdevices within a network, such as: A Cellular Mobile Telephone SystemWith Load Sharing—An Enhancement Of Directed Retry; Karlsson, J.;Eklundh, B.; IEEE Transactions on Communications; May 1989;Investigating the Energy Consumption of an IEEE 802.11 NetworkInterface, Laura Marie Feeney, Swedish Institute of Computer Science,December 1999; IEEE 802.11 Tutorial, Mustafa Ergen, University ofCalifornia Berkeley, June 2002; Minimizing Energy for Wireless WebAccess with Bounded Slowdown, Ronny Krashinsky, Hari Balakrishnan, MITLaboratory for Computer Science, September 2002; M-RPC: A RemoteProcedure Call Service for Mobile Clients; Ajay Bakre; B. R. Badrinath;Department of Computer Science, Rutgers, The State University of NewJersey; J. Kawan; Wireless Transaction And Information System; U.S. Pat.No. 6,442,532; I. Gerszberg, R. Miller, J. Russell, and E. Wallace;Integrated Services Director (ISD) Overall Architecture; U.S. Pat. No.6,424,646; R. James, D. Nash, and J. Rogers; Apparatus And Method For AnEnhanced PCS Communication System; U.S. Pat. No. 6,219,537; R, Farris,and W. Goodman; Mobile Voice Message/Electronic Mail System; U.S. Pat.No. 6,151,491; M. Chen, K. Wu, and P. Yu; Information Handling SystemAnd Method For Maintaining Coherency Between Network Servers And MobileTerminals; U.S. Pat. No. 6,128,648; M. Cudak, and M. Pearce; Method,Access Point Device And Peripheral Devices For Low Complexity DynamicPersistence Mode For Random Access In A Wireless Communication System;U.S. Pat. No. 5,862,452; L. Tymes, and G. Ennis; Protocol For PacketData Communication System; U.S. Pat. No. 5,668,803; L. Tymes, and J.Kramer; Packet Data Communication System; U.S. Pat. No. 5,479,441;Two-Way Wireless Messaging System With Flexible Messaging; EuropeanPatent Number EP 825788; A. Rossmann; Method And Architecture For AnInteractive Two-Way Data Communication Network; U.S. Pat. No. 6,430,409;N. Rydbeck, B. Molnar, J. Guey, A. Khayrallah, and R. Koilpillai;Wireless Communications Systems With Standard And Robust Services AndMethods Of Operation Thereof; U.S. Pat. No. 6,320,843; B. Persson, andJ. Turcotte; Method For Communicating In A Wireless CommunicationSystem; U.S. Pat. No. 6,144,653; S. Boyle, P. King, B. Martin, A.Rossmann, and B. Schwartz; Pushing And Pulling Data In Networks; U.S.Pat. No. 6,119,167; G. Rai, P. Parsons, and M. Chuah; Efficient MobilityManagement Scheme For A Wireless Internet Access System; U.S. Pat. No.6,421,714; M. Doviak, D. Whitmore, and F. Houvig; Apparatus And MethodFor Transparent Wireless Communication Between A Remote Device And HostSystem; U.S. Pat. No. 6,418,324; R. Scheibel, and R. Boxall; Method AndApparatus For Conveying Data Between Communication Devices; U.S. Pat.No. 6,212,240; R. Snelling, P. McIntosh, J. Taylor, and M. Tucker;Communications Webs With Personal Communications Links For PSTNSubscribers; U.S. Pat. No. 6,404,761; J. Kubler, and M. Morris;Hierarchical Data Collection Network Supporting Packetized VoiceCommunications Among Wireless Terminals And Telephones; U.S. Pat. No.6,389,010; J. Kubler, and M. Morris; Hierarchical Data CollectionNetwork Supporting Packetized Voice Communications Among WirelessTerminals And Telephones; U.S. Pat. No. 5,726,984; R. Mahany;Hierarchical Communications System Using Microlink, Data Rate Switching,Frequency Hopping And Vehicular Local Area Networking; U.S. Pat. No.5,696,903; K. Rowney; System, Method And Article Of Manufacture ForTransmitting Messages Within Messages Utilizing An Extensible, FlexibleArchitecture; U.S. Pat. No. 6,373,950; G. Anderson, S. Gavette, C.Lindsay, and R. Jensen, Communication System And Method; U.S. Pat. No.6,094,575; D. Haller, T. Nguyen, K. Rowney, D. Berger, and G. Kramer;System, Method And Article Of Manufacture For Managing Transactions In AHigh Availability System; U.S. Pat. No. 6,026,379; D. Kandasamy, M.Butler, A. Foss, B. Peterson, C. Patwardhan, M. Ribble, D. Rothmaier,and G. Ramil; Fault Tolerant NFS Server System And Mirroring Protocol;COMPUTER SYSTEM; U.S. Pat. No. 5,513,314; Method For TransferringResource Information; European Patent Number EP 1148681; Method AndSystem For Providing Connection Handling; European Patent Number EP1175066; Universal Mobile Telecommunications System (UMTS) Quality OfService (Qos) Supporting Variable Qos Negotiation; European PatentNumber EP 1233578; Method For Achieving End-To-End Quality Of ServiceNegotiation For Distributed Multimedia Applications; European PatentNumber EP 1248431; Communications System And Method IncludingEnergy-Efficient Caching For Mobile Computing; European Patent Number;EP 714066; S. Alanara, and S. Willhoff; Methods And Apparatus ForProviding Delayed Transmission Of SMS Delivery Acknowledgement, ManualAcknowledgement And SMS Messages; U.S. Pat. No. 5,878,351; T. LaPorta,K. Sabnani, and T. Woo; Two-Way Wireless Cellular Messaging System; U.S.Pat. No. 5,974,300; G. Kramer; System, Method And Article Of ManufactureFor A Modular Gateway Server Architecture; U.S. Pat. No. 6,002,767; M.Cudak, B. Mueller, J. Kelton, and B. Glasson; and Network ProtocolMethod, Access Point Device And Peripheral Devices For Providing For AnEfficient Centrally Coordinated Peer-To-Peer Wireless CommunicationsNetwork; U.S. Pat. No. 6,058,106.

The disclosed prior art systems and methodologies thus providecommunication architectures and protocols for wireless devices within anetwork. However, for many wireless devices having limited powerresources, the communication architectures and protocols require a largeenergy expenditure to exchange information.

It would therefore be advantageous to provide a datagram protocolsystem, which limits the power expenditure of wireless devices. Thedevelopment of such a protocol system would constitute a majortechnological advance.

Furthermore, it would be advantageous to provide a datagram protocolsystem structure and process, which limits the power expenditure ofwireless devices by limiting the transmission of frames from a wirelessdevice. The development of such a datagram protocol system wouldconstitute a further technological advance.

In addition, it would be advantageous to provide a datagram protocolsystem which limits the power expenditure of wireless devices through anasymmetrical retry mechanism between a wireless device and a server,which reduces the transmission of retry frames from the device. Thedevelopment of such a datagram protocol system would constitute afurther technological advance.

As well, it would be advantageous to provide a datagram protocol systemstructure and process which comprises acknowledgement frames whichinclude information regarding other data, whereby knowledge of thetransmission or receipt of a plurality of data frames is containedwithin an acknowledgement of a single frame of data. The development ofsuch a datagram protocol system would constitute a further majortechnological advance.

SUMMARY OF THE INVENTION

Systems are provided for sequencing, delivery acknowledgement, andthrottling of data packets over a network layer, such as UDP and SMS. Tosupport devices with limited battery resources, the inventionincorporates asymmetric retry logic and/or acknowledgements withoverlapping ranges, to minimize the transmissions required for thedevice. The sender of a data-bearing frame does not need to wait for aframe to be acknowledged before sending the next, such that many framescan be “in flight” at once.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of wireless devices in wireless communicationwith a server;

FIG. 2 is a schematic view of a wireless datagram transaction protocol(WDTP) system;

FIG. 3 is a detailed schematic view of a wireless device wirelessdatagram transaction protocol (WDTP) communication between a device anda server;

FIG. 4 is a detailed schematic view of a wireless communication systembetween a first portable device and a second portable device;

FIG. 5 is a detailed schematic view of an alternate wirelesscommunication system between a wireless first device and an externallypowered second device;

FIG. 6 is a detailed schematic view of an alternate prioritized wirelesscommunication system between a first device and a second device;

FIG. 7 is a schematic view of frame communication and asymmetric retrywithin a wireless device wireless datagram transaction protocol (WDTP)system;

FIG. 8 is a schematic view of DATA frame sequence number processing anda is wrapped sequence number series;

FIG. 9 is a schematic view of a frame header in the wireless datagramtransaction protocol system;

FIG. 10 is a schematic view of an INIT frame in the wireless datagramtransaction protocol system;

FIG. 11 is a schematic view of a READY frame in the wireless datagramtransaction protocol system;

FIG. 12 is a detailed schematic view of a DATA frame in the wirelessdatagram transaction protocol system;

FIG. 13 shows a detailed schematic view of an acknowledgement ACK framein the wireless datagram transaction protocol system;

FIG. 14 is a detailed schematic view of a RETRY frame in the wirelessdatagram transaction protocol system;

FIG. 15 is a detailed schematic view of a WINDOW frame in the wirelessdatagram transaction protocol system;

FIG. 16 is a detailed schematic view of a RESET frame in the wirelessdatagram transaction protocol system;

FIG. 17 is a detailed schematic view of an ERROR frame in the wirelessdatagram transaction protocol system;

FIG. 18 is a flowchart of a process for determining whether a window isopen to send a DATA frame;

FIG. 19 is a detailed flowchart of a process for computing a window inthe WDTP system;

FIG. 20 is a detailed flowchart of a process for checking to see if awindow is open to send a DATA frame;

FIG. 21 is a flowchart showing validation for inbound DATA Framesequence numbers;

FIG. 22 is a flowchart showing rules for updating the next sequencenumber in and the next sequence number out;

FIG. 23 is a flowchart showing a class for handling wrapping sequencenumbers;

FIG. 24 and FIG. 25 show operator methods for wireless datagramtransaction protocol (WDTP) sequence numbers;

FIG. 26 is a flowchart showing a class for handling the processing ofwindows comprising sequence numbers;

FIG. 27 is a flowchart showing an implementation of construction for awireless datagram transaction protocol (WDTP) window;

FIG. 28 is a table of server timeout rules in the WDTP system;

FIG. 29 is a table of device timeout rules in the WDTP system;

FIG. 30 and FIG. 31 show process flow in the WDTP system with no errors;

FIG. 32 shows a process for sending DATA frames and acknowledgement ACKframes between a device and a server;

FIG. 33 shows a detailed process for sending acknowledgement ACK framesbetween a server and a device;

FIG. 34 shows error categories and associated process flows within awireless datagram transaction protocol (WDTP) system;

FIG. 35 shows error scenarios and responses for lost INIT Frames andREADY Frames;

FIG. 36 shows error scenarios and responses for lost DATA Frames;

FIG. 37 shows error scenarios and responses for lost ACK Frames;

FIG. 38 shows error scenarios and responses for a lost RETRY Frame;

FIG. 39 shows error scenarios and responses for a lost WINDOW Frame;

FIG. 40 shows error scenarios and responses for a lost RESET Frame;

FIG. 41 shows an error scenario and response for a lost ERROR Frame;

FIG. 42 shows error scenarios and responses for a duplicate Framereceived;

FIG. 43 shows error scenarios and responses the arrival of a bogus framehaving a valid header;

FIG. 44 shows error scenarios and responses for a Frame received with aninvalid frame type;

FIG. 45 shows error scenarios and responses for a Frame received with anInvalid sequence number;

FIG. 46 shows error scenarios and responses for a DATA Frame which isreceived before an INIT Frame;

FIG. 47 shows error scenarios and responses for an INIT Frame which isreceived after a DATA Frame;

FIG. 48 and FIG. 49 show WDTP System process flow through an Initsequence with timeouts;

FIG. 50 shows beginning device and server states for DATA, ACK, WINDOW,and RETRY processes;

FIG. 51 shows exemplary state interactions between a device and aserver, when the device sends two DATA Frames, and the first neverarrives at the server;

FIG. 52 shows exemplary state interactions between a device and aserver, when the device sends three DATA Frames, wherein the first andsecond Frames never arrive at the server, and wherein the WINDOW isclosed for the third Frame;

FIG. 53 shows exemplary state interactions between a device and aserver, when the server sends two DATA Frames, and the first neverarrives at the device;

FIG. 54 shows exemplary state interactions between a device and aserver, when the device sends an ACK Frame, which never arrives at theserver;

FIG. 55 shows exemplary state interactions between a device and aserver, when the server receives an unexpected Frame while in theRunning state; and

FIG. 56 shows exemplary state interactions between a device and aserver, when the server receives an unexpected Frame while in theStopped state.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a schematic plan view of a wireless communication system 10 a,between a wireless device 12 and a secondary device 14, such as a server14. Examples of portable wireless devices 12 currently comprise but arenot limited to cellular phones 12 a, portable, i.e. laptop computers 12b, personal digital assistants PDAs 12 c having communicationscapabilities, and/or gaming devices 12 d having communicationscapabilities.

Wireless devices 12 typically comprise a portable energy, i.e. battery,storage 54 (FIG. 3), by which a wireless device can be operated as aportable device. For portable operation, a communication link 20 from awireless device 12 comprises a wireless signal 18 (FIG. 2), throughwhich packets 17 are transmitted and received.

FIG. 2 is a schematic plan view of an exemplary wireless communicationsystem 10 b, between a wireless device 12 and a secondary device 14,such as a server 14. As seen in FIG. 2, an intermediate wireless carrier22, comprising a base station 24 connected to a network interface 26, islocated between the wireless device 12 and a server 14 at a host complex30. A secondary link 28, such as through a network or Internet 29, islocated between the wireless carrier 22 and the host complex 30. Thecommunication link 20 shown in FIG. 2 comprises both a wireless signal18 between the wireless device 12 and the wireless carrier 22, as wellas the secondary link 28, such as a wired or wireless link 28, betweenthe wireless carrier 22 and the server 14 at the host complex 30.

FIG. 3 is a detailed schematic view of a wireless communication system10 c, in which wireless communication complies with a wireless datagramtransaction protocol (WDTP) system 100 (FIG. 7), which comprises anasymmetric exchange of packets 17 across a communication link 20, suchthat the energy expenditure 54,56 (FIG. 3) is minimized for the wirelessdevice 12.

The wireless device 12 shown in FIG. 3 comprises a transceiver 42 and anantenna 44, by which a wireless signal 16, comprising a forward link 38,which is transmitted from the wireless device 12, and a reverse link 40,which is received by the wireless device 12. The wireless device 12 inFIG. 3 comprises a processor 46, communication logic 48, and a userinterface 51. A device identifier 50 is also typically associated withthe wireless device 12.

The wireless device 12 also comprises a power system 52, comprising abattery 54 having limited energy storage 56 a-56 n, such as arechargeable or replaceable battery 54. Wireless devices 12 oftenfurther comprise means for wired operation, such as a power module 58which is connectable to external power 60. A power bus 62 is connectedbetween the power system 52 and device componentry, such as theprocessor 46.

Wireless devices 12 typically operate in a portable environment, inwhich a portable battery 54 is required. While the physical size andweight of portable batteries 54 has decreased over time, total operationtime for a battery 54 is still limited by the available capacity 56 a-56n of the battery 54 and the power requirements of the wireless device12.

While the wireless datagram transaction protocol system 100 can be usedto support communication across any communication system 10, thewireless datagram transaction protocol system 100 is ideally suited tosupport wireless devices 12 having limited battery resources 54,56,since WDTP incorporates an asymmetric retry logic that minimizestransmissions required by the portable device 12. WDTP is readilyadapted to applications which communicate over a wireless network, suchas a TDMA based wireless packet network, e.g. a GPRS or an EDGE network,or a CDMA based wireless packet network, e.g. a 1xRTT or a 1xEV network.

As seen in FIG. 2, packets 17 are comprised of structured datagrams 19,which conform to the wireless communication network 21. The wirelessdatagram transaction protocol system 100 is readily adapted to a widevariety of datagram structures 19.

While the wireless datagram transaction protocol system 100 is typicallyimplemented for device-server communications, alternate embodiments ofthe wireless datagram transaction protocol system 100 providesdevice-device communications.

FIG. 4 is a detailed schematic view of a wireless communication system10 d between a first device 12 a and a second device 12 b. As seen inFIG. 4, the wireless devices 12 a,12 b each have a power system 52,comprising a battery 54 having limited energy storage 56 a-56 e, such asa rechargeable or replaceable battery 54. While the wireless devicesshown in FIG. 4 also comprise a power module 58 which is connectable toexternal power 60, both wireless devices 12 a,12 b are operating in awireless environment. As seen in FIG. 4, the energy storage 56 a-56 c ofthe first wireless device 12 a is charged 57, while energy storage 56d,56 e is depleted 59. Also as seen in FIG. 4, the entire energy storage56 a-56 e of the second wireless device 12 b is charged 57.

In the wireless communication system 10 d shown in FIG. 4, a storedenergy handshake 82 is exchanged between the wireless devices 12 a,12 b,such that the wireless datagram transaction protocol system 100 may beused, as necessary, to conserve battery resources as needed. Forexample, during initial communication between the devices, the storedenergy capacity 56, e.g. such as battery storage level or availableoperating time, is communicated and compared between the wirelessdevices 12 a,12 b.

In the scenario shown in FIG. 4, the available capacity 56 of the firstwireless device 12 a is less than the available capacity 56 of thesecond wireless device 12 b, such that the wireless datagram transactionprotocol system 100 may be implemented to conserve power of the firstwireless device 12 a. For example, as a result of the stored energyhandshake 82, the device 12 having a greater energy storage 56, e.g. thesecond device 12 b, assumes the role of a virtual server 14 v, wherebythe WDTP system 100 operates the second device 12 b as a server 14, asdescribed herein, i.e. assuming the role of a server 14, to conserve theavailable power 56 for the first wireless device 12 a.

FIG. 5 is a detailed schematic view of an alternate wirelesscommunication system 10 e between a first device 12 a and a seconddevice 12 b. As seen in FIG. 5, the wireless devices 12 a,12 b each havea power system 52, comprising a battery 54 having limited energy storage56 a-56 n, such as a rechargeable or replaceable battery 54. While thewireless devices 12 a,12 b shown in FIG. 5 also comprise a power module58 which is connectable to external power 60, the first device 12 a isoperating in a wireless environment, while the second device isconnected to supplied external power 60.

As seen in FIG. 5, while the energy storage 56 a-56 d of the firstwireless device 12 a is charged 57 to a greater level than the energystorage 56 a,56 b of the second device 12 b, the second device isconnected to supplied external power 60, such that the second device 12b has less need to conserve battery storage 56, i.e. the device isoperated as a wired device 12, whereby the battery 54 is also typicallycharged.

In the wireless communication system 10 e shown in FIG. 5, an energysource handshake 86 is exchanged between the wireless devices 12 a,12 b,such that the wireless datagram transaction protocol system 100 may beused, as necessary, to conserve battery resources as needed. Forexample, during initial communication between the devices 12 a,12 b, thecurrent power source 54,60 for each device 12 is compared 86, such thata wired device, e.g. the second device 12 b, may be operated as avirtual server 14 v, to conserve power 56 of the wireless device 12 a.

FIG. 6 is a detailed schematic view 88 of an alternate wirelesscommunication system 10 f between a first device 12 a and a seconddevice 12 b. As seen in FIG. 6, the wireless devices 12 a,12 b each havea power system 52, comprising a battery 54 having limited energy storage56 a-56 e, such as a rechargeable or replaceable battery 54. As well,each of the devices further comprises a device priority 92, such thatthe wireless datagram transaction protocol system 100 may be applied asa function of priority 92, whereby the priority 92 of devices 12 iscompared 90 to determine either energy conservation status or virtualserver status. In the exemplary embodiment 10 f seen in FIG. 6, whilethe available power capacity 56 of the second device 12 b is lower thanthe available power capacity 56 of the first device 12 a, the priority92 of the first device 12 b may prevent the first device 12 a fromoperating as a virtual server 14 v.

In the alternate wireless communication system 10 f, the first device 12a has a higher priority 92 than the second device 92, such that otherdevices 12, e.g. such as device 12 b, are required to communicate eitheras a virtual server 14 v, or as an equal device, such as in symmetricmanner.

FIG. 7 is a schematic view of a wireless datagram transaction protocol(WDTP) system 100, in which WDTP frames 101 are controllably exchangedbetween a wireless device 12 and a server 14, and comply with a wirelessdatagram transaction protocol 107. The WDTP frames 101 comprise INITframes 102, READY frames 104, DATA frames 106, acknowledgement ACKframes 110, RETRY frames 114, WINDOW frames 116, RESET frames 118, andERROR frames 120, as well as supplementary RESERVED frames 122. Thewireless datagram transaction protocol system 100 provides sequencing,delivery acknowledgement 110 and throttling, i.e. through a slidingwindow 124,126 of datagram packets 17 carried over a network layer 21,and advantageously provides asymmetric retry within a wireless devicewireless datagram transaction protocol (WDTP) system, such that storedpower resources of a wireless device are conserved.

Uses for Wireless Datagram Transaction Protocol (WDTP).

The wireless datagram transaction protocol system 100 providessequencing, delivery acknowledgement and throttling of datagram packets17 carried over a network layer 21, that typically provides a moderatelevel of error checking such as UDP and SMS. WDTP DATA frames 106 aretypically used to carry an ordered stream of data 180 (FIG. 12), orarbitrarily ordered data 180.

To support devices with limited battery resources 54,56, the wirelessdatagram transaction protocol system 100 incorporates asymmetric retrylogic that minimizes the transmissions required by the device 12.Typical embodiments of the wireless datagram transaction protocol system100 provide communication over a wireless network, such as GPRS or1xRTT.

While the wireless datagram transaction protocol system 100 is typicallyimplemented for device-server communications, device-devicecommunications are still possible with this protocol, such as forembodiments in which asymmetrical retry logic may be beneficial. Forexample, in communications systems between wireless devices havinglimited battery resources, an initial handshake between devices canpreferably include a comparison of available power 54,56, whereby thedirection of asymmetric logic can be determined to preserve power forthe device having the lowest power capacity 54,56.

Error Recovery.

WDTP uses validity checking based on the frame type 101, to catch mostprotocol errors that slip through the network layer's error checking.There are no “fatal” protocol errors that cause the WDTP connection tobe dropped. Severe protocol errors will induce a reset process 118.Minor protocol errors are mostly ignored, i.e. when a minor protocolerror is detected, the error is typically discarded, with no errormessage passed to higher layers of controlling software. Recovery frompacket loss as a result of minor protocol errors is accomplished withretry mechanisms 114,116. WDTP recovers 100 from network layer errorswith the same retry mechanisms used to recover from minor protocolerrors.

Basic Approach to Frame Delivery.

WDTP 100 requires that each DATA frame 106 carrying data eventually beacknowledged. However, the sender of a data-bearing frame 106 does notneed to wait for one to be acknowledged before sending the next, suchthat many DATA frames 106 can be “in flight” at once. The size of thewindow (number of data frames that can be sent at once) is set during aninitialization handshake. Lost data and acknowledgement frames are sentby a retry mechanism.

Datagram Layers.

Unique Device Identification.

Communications layers below WDTP are able to uniquely identify thesource of a datagram 19, so that the contents of a datagram 19 aredelivered to the right destination. While source identification is oftenachieved with an IP address, in a wireless environment, such as GPRS,the IP address assigned to a device may change from time to time,possibly during the same online session.

Therefore, a wireless device 12 must be uniquely identified by somethingother than IP address. SMS datagrams provide this unique identifier inthe SMS header; it is the MS-ISDN. UDP datagrams do not carry anythingto uniquely identify the source other than the IP address. Thus, forUDP, there must be another protocol layer above UDP, but below WDTP, tocarry a unique identifier, as shown:

1 IP><UDP><Unique-ID Protocol><WDTP+data>.  (1)

Replying to the Device.

In the SMS case, the server 14 replies to the device 12 by sending areply SMS to the source MS-ISDN. In the UDP case, wherein the Internetrouting protocol does not include an identifier that is guaranteed to beunique, the server 14 relies on the source IP address and port of thelast UDP 15 (FIG. 1) received from the device 12, wherein the source IPaddress and port are contained in the IP layer of the protocol.Therefore, since the source IP address may change arbitrarily, theserver 14 saves the source IP address and port each time a valid UDP 15is received. If the source IP address changes, the server does not know,whereby any UDP datagrams sent by the server 19 would be sent to thewrong IP address, until the device sends another datagram 19.

Importance of Encryption.

The SMS network layer guarantees that the MS-ISDN contained in the SMSheader is authentic, i.e. that the SMS really came from the device 12 itsays it came from. This is not true for the Unique-ID Protocol. Unlessthe Unique-ID protocol is encrypted, any device 12 can send a UDP withanother Device's unique identifier. The server 14 would then save thewrong Device's IP address and start sending replies to the wrong Device.Unfortunately, encrypting the Unique-ID Protocol requires gatewayservers to maintain encryption state. To avoid that requirement, it issufficient to encrypt the WDTP frames.

<IP><UDP><Unique-ID Protocol><Encryption Protocol><encrypted(WDTP+data)>  (2)

or, less secure but more efficient in terms of number of bytes (sincenot all WDTP frames contain data):

<IP><UDP><Unique-ID Protocol><WDTP+encrypted data>  (3)

The server can then ignore any datagrams which fail to decrypt properly,not even updating the source IP and port.

Header Format.

FIG. 9 is a schematic view of a frame header 146 in the wirelessdatagram transaction protocol system 100, comprising a CRC 148, a frametype identifier 151, and a sequence number identifier 153. The totalsize of the header 146 is typically four bytes, as shown:

$\begin{matrix}{\underset{2\mspace{14mu} {bytes}}{\langle{16\text{-}{bit}\mspace{14mu} {CRC}}\rangle}\underset{2\mspace{14mu} {bytes}}{\langle{{frame}\mspace{14mu} {type}\text{:}\mspace{11mu} {sequence}\mspace{14mu} {number}}\rangle}} & (4)\end{matrix}$

The frame type identifier 151 and sequence number identifier 153 aretypically stored within 2 bytes, wherein the first four bits determineframe type 151, and the remaining twelve bits identify 153 the sequencenumber (0.4095=0xOFFF). A 16-bit CRC 148 uses a standard CRC-16polynomial: x¹⁶+x¹⁵+x²+1, which is different from the 16-bit CRC-CCITTpolynomial. The CRC 148 is computed over the frame type, sequencenumber, and payload of the frame.

The wireless datagram transaction protocol system 100 seen in FIG. 7presently comprises eight WDTP frame types 101, comprising INIT frames102, READY frames 104, DATA frames 106, acknowledgement ACK frames 110,RETRY frames, 114, WINDOW frames 116, RESET frames 118, and ERROR frames120. Supplementary RESERVED frames 122 are also provided in someembodiments of the wireless datagram transaction protocol system 100, toprovide further system functionality. An overview of WDTP frame types isseen in Table 1.

TABLE 1 Frame type 4-bit encoding Frame size (including payload) INIT0000 8 bytes READY 0001 6 bytes DATA 0010 >6 bytes (variable) ACK 0011 6bytes RETRY 0100 12 bytes WINDOW 0101 4 bytes RESET 0110 6 bytes ERROR0111 6 bytes <Reserved> 1000 . . . 1111

Sequence Number.

FIG. 8 is a schematic view of DATA frame sequence number processing 130and a wrapped sequence number series 140. In some embodiments of thewireless datagram transaction protocol system 100, the associatedsequence number 108 for a DATA frame 106 is in the range from sequencenumber 0 142 a to sequence number 4095 142 n, and simply wraps around144, which can be used in embodiments wherein there are no more than 4Kof DATA frames 106 buffered. In embodiments of the wireless datagramtransaction protocol system 100 having a maximum buffer window size of1024 DATA frames 106, a wrapped sequence number series 140 having 0 . .. 4095 sequence numbers 142 a-142 n is more than sufficient.

The sequence number field 108,112 (FIG. 7) in the header 146 (FIG. 9) isused for different purposes, depending on the frame type 101. Only DATAframes 106 are actually sequenced. Thus, only DATA frames 106 have anassigned sequence number 176 (FIG. 12), i.e. assigned to them. Thesequence number 153 in the header 146 of a DATA frame 106 truly is thatframe's sequence number 176. In most other frame types 101 that are notsequenced, the sequence number 153 indicates which DATA frame 106 to actupon. For example, the sequence number 153,112 in an ACK frame 110indicates which DATA frame 106 is being acknowledged.

Frame Formats.

INIT Frame.

FIG. 10 is a schematic view 150 of an INIT frame 102 in the wirelessdatagram transaction protocol system 100. A header 146 comprises a CRC152, a frame type identifier 151, and a sequence number 153. The INITframe 102 also comprises an init_key 156, a version number ID 158, and awindow_size identifier 160, as shown:

<crc><0000:seqnum><init_key><version><window_size>  (5)

The relative size of the INIT frame 102 elements is shown in Table 2. Avalid INIT frame 102 typically comprises 8 bytes.

TABLE 2 crc  2 bytes CRC of the frame seqnum 12 bits sequence number ofthe next DATA frame init_key  2 bytes used to ensure INIT frames matchversion  1 byte protocol version number window_size  1 bytein_window_size of the sender of this frame

An INIT frame 102 is sent by each side, e.g. by both a wireless device12 and a server 14, to exchange starting sequence numbers 153, and toset the window size for throttling DATA frames 106. The device 12 isresponsible for sending (and resending upon a timeout) the first INITframe 102. DATA frames 106 are not sent until the sender is notifiedthat its INIT frame 102 has been received, whereby notification ofreceipt is accomplished with the transmittal and receipt of a READYframe 104. In typical system embodiments between a wireless device 12and a stationary server 14, communication is prompted by action of thewireless device 12, i.e. the server 14 never sends the first INIT frame102.

Once the initialization sequence is complete, it is an error for theserver 14 to receive an INIT frame 102 from the device 12, whereby, theserver 12 would properly reply with an ERROR frame 120 (FIG. 7). Priorto completion of the initialization sequence, wherein READY frames 104are exchanged, the server 104 must always reply with its own INIT frame102 each time it receives an INIT frame 102 from the device 12.

INIT Frame seqnum Field.

The sequence number field 153 in the header 146 specifies the sequencenumber 176 of the next DATA frame 104 that will be sent.

The sender may initialize this value arbitrarily in the range {0 . . .4095}, and store it in a variable called next_seqnum_out 138 (FIG. 8).

When an INIT frame 102 is received, the receiver stores its sequencenumber 153 in a variable called next_seqnum_in 136. The next DATA frame106 to be received is expected to have a sequence number ofnext_seqnum_in 136.

INIT Frame init_key Field.

The device 12 computes the init_key 156 arbitrarily before sending itsINIT frame 102 to the server 14, and server 14 uses the same init_key156 in its reply INIT frame 102. If the device 12 times out waiting forthe server's reply INIT frame 102, the device computes a new anddifferent init_key 156 before resending its INIT frame 102 to the server14.

INIT Frame Version Field.

The INIT frame version field 158 is used to confirm the version of theprotocol system 100. For example, in a current version 158 of theWireless datagram transaction protocol system 100, the version field 158is set to {1}. The version number is incremented, as necessary, basedupon modification of the Wireless datagram transaction protocol system100.

If a device 12 sends an INIT frame 102 with a version 158 that is notsupported by the server 14, the server 14 preferably responds toindicate that the requested version of the protocol is not supported.For example, the server 14 may respond with an INIT frame having theversion 158 set to 0, wherein a version 158 set to 0 indicates that therequested version of the protocol is not supported.

INIT Frame window_size Field.

As seen in FIG. 7, both the server 14 and the device 12 have variablescalled in_window_size 124 and out_window_size 126. These variables124,126 are used for determining whether the ‘window is open’ totransmit an outbound DATA frame 106, and to validate the associatedsequence number 108 of an inbound DATA frame 106.

The window_size field 160 in the INIT frame 102 is in the range {0 . . .255}, but it is multiplied by 4 to obtain the actual window size. Thespecial value 0 indicates a window of 1024 frames.

The sender, e.g. a device 12 or server 14, of an INIT frame 102 sets thewindow_size field 160 to its own in_window_size 124. The receiver of anINIT frame 102 sets its out_window_size 126 equal to the window_sizefield 160 in the INIT frame 102. Table 3 summarizes the use ofin_window_size 124 and out_window_size 126 fields.

TABLE 3 Variable Definition Device::in_window_size maximum number ofinbound DATA frames that can be buffered by the DeviceDevice::out_window_size maximum number of inbound DATA frames that canbe buffered by the Server Server::in_window_size maximum number ofinbound DATA frames that can be buffered by the ServerServer::out_window_size maximum number of inbound DATA frames that canbe buffered by the Device.

Table 4 summarizes the logic states for the device 12 and server 14after the INIT frames 102 have been exchanged, i.e. the following statesshould be true:

TABLE 4 Server Device next_seqnum_in equals next_seqnum_outnext_seqnum_out equals next_seqnum_in in_window_size equalsout_window_size out_window_size equals in_window_size

Ready Frames.

FIG. 11 is a schematic view 162 of a READY frame 104 in the wirelessdatagram transaction protocol system 100. A READY frame 104 is sent toacknowledge receipt of the INIT frame 102, and to establish the ResetKey 166. No DATA frames 106 are sent until a READY frame 104 isreceived. The READY frame 104 comprises a CRC 164 and a reset key 166,wherein the reset key 166 is comprised of a reset_key_A 168 and arest_key_B 170, as shown:

<crc><0001:reset_key_a><reset_key_b>  (6)

The relative size of the READY frame 104 elements is shown in Table 5. Avalid INIT frame 102 typically comprises six bytes.

TABLE 5 crc  2 bytes CRC of the frame reset_key_a 12 bits part of first2 bytes of the reset key reset_key_b  2 bytes last 2 bytes of the resetkey

The device 12 is responsible for timing out and resending a READY frame104, in a similar manner to the communication of INIT frames 102. Anytime the server 14 receives a READY frame 104, the server 14 properlyreplies with an identical READY frame 104. In most embodiments of theWireless datagram transaction protocol system 100, since the ready stateis initiated by the device, the device 12 does not properly reply to areceived READY frame 104.

If the device 12 receives a DATA frame 106 when it is expecting a READYframe 104, the device may assume that the server 14 received thedevice's READY frame 104. The READY frame 104 from the server 12 maycome later, or may never arrive. In either case, the device 12 does notneed to resend its READY frame 104.

READY Frame Reset Key.

The Reset Key 166 typically comprises a 28 bit value, with a range of0.256M. The Reset Key 166 is also sent as part of a RESET frame 118, ifa RESET frame 118 ever becomes necessary. The purpose of the Reset Key166 is to verify that the sender of a RESET frame 118 is actually theowner of the WDTP connection.

The device 12 computes the Reset Key 166 arbitrarily at the beginning ofthe initialization process. If the READY frame 104 must be resentbecause of a timeout, the Reset Key is not recomputed. Both the device12 and the server 14 store the Reset Key 166 as part of the connectioninformation.

READY Frame reset_key_a Field and reset_key_b Field.

The reset_key_a field 168 holds the first 12 bits of the Reset Key 166,while the reset_key_b field 170 is holds the last 2 bytes of the ResetKey 166.

READY Frame Validation Check.

In one embodiment of the Wireless datagram transaction protocol system100, a valid READY frame 104 always has exactly 6 bytes, such that thedevice 12 can compare a READY frame 104 it receives from the server 14to a READY frame 104 which was sent to the server, to confirm thevalidity of the received READY frame 104.

Data Frames. FIG. 12 is a schematic view of a DATA frame 106 in thewireless datagram transaction protocol system, comprising a CRC 174, andassociated sequence number 176, a data length 178, and data 180, asshown:

<crc><0010:seqnum><data_length><data>  (7)

A DATA frame 106 is only sent after the initialization process iscomplete. If the server receives a DATA frame 106 before initializationhas started, the server 14 replies with an ERROR frame 120. If theserver 14 receives a DATA frame 106 during initialization, the server 14ignores the frame 106. Similarly, if the device 12 receives a DATA frame106 before or during initialization, the device 12 ignores the frame106. The relative size of the DATA frame 104 elements is shown in Table6.

TABLE 6 crc 2 bytes CRC of the frame seqnum 12 bits the sequence numberof this DATA frame data_length 2 bytes the number of bytes in the datafield data n bytes the data

Data Frame seqnum Field.

The sender of a DATA frame 106 sets the seqnum field 176 to the nextnumber in the sequence. The next_seqnum_out variable 138 (FIG. 8) is notincremented until a DATA frame 106 is actually sent.

Data Frame data_length Field.

In one embodiment of the wireless datagram transaction protocol system100, the maximum amount of data that can be carried by a DATA frame 106is 64K bytes. In alternate embodiments of the Wireless datagramtransaction protocol system 100, the datagram protocol which is used totransport a DATA frame 106 limits the amount of data per DATA frame toan amount less than 64K bytes. For example, UDP has a maximum size of1536 data bytes, although some implementations only allow 1024 databytes. Thus, the maximum data size for a DATA frame 106 transported viaUDP is 1018 bytes (1024 minus 6 bytes of header).

Data Frame Data Field.

The data field 180 contains ‘data_length’ bytes of the stream beingtransmitted. A wide variety of data types can be used, such as but notlimited to 7-bit data, 8-bit data, encrypted data, or non-encrypteddata.

Data Frame Processing.

When a DATA frame 106 is received that is within the window of validsequence numbers 176, but is not the next_seqnum_in 136 expected, thereceiver must add the DATA frame 106 to its inbound queue 135 and keeptrack of which DATA frames 106 are missing. Since DATA frames 106 areprocessed in sequential order, DATA frames 106 which are received out oforder must be held in queue 135 until the missing DATA frames 106 arereceived. One way to accomplish this is to add empty DATA frames to theinbound queue to fill in the holes. The state of an empty DATA frame canbe set to “missing”. As the missing DATA frames arrive, simply replacethe “missing” placeholder with the real DATA frame and set its state to“ready”.

Data Frame Validation Check.

In a current embodiment of the Wireless datagram transaction protocolsystem 100, the total size of a valid DATA frame is always be greaterthan 6 bytes, and the total size of a valid DATA frame 106 should beequal to data_length+6.

ACK Frames.

FIG. 13 shows a schematic view 182 of an acknowledgement ACK frame 110,comprising an ACK frame CRC 184, an acknowledged sequence number 112, anat top field 186, a leading ACKs field 188, and a following ACKs field190, as shown:

<crc><0011:seqnum><at_top:leading_acks><following_acks>  (8)

An ACK frame 110 is sent by a recipient, such as a device 12 or a server14, in response to each DATA frame 106 received. No other frame types101 are acknowledged by an ACK frame 110. As soon as an ACK frame 110 isreceived, the DATA frame 106 with the matching sequence number 108 maybe deleted from the outbound queue 131 (FIG. 8). The relative sizes ofexemplary ACK frame elements are shown in Table 6.

TABLE 7 CRC  2 bytes CRC of the frame Seqnum 12 bits the sequence no. ofthe DATA frame recd, now being ACK'd at_top  1 bit Boolean: true ifthere are no “missing” DATA frames prior to the DATA frame being ACK'dleading_ac  7 bits number of received DATA frames preceding ks andcontiguous to seqnum following_a  8 bits number of received DATA framesfollowing and cks contiguous to seqnum

“Overlapping” ACK frames. Preferred embodiments of the wireless dataprotocol system 100 comprise an overlap of ACK frames 110 for arecipient, such as for a wireless device 12 or a server 14. The overlapof ACK frames 110 helps compensate for lost ACK frames 110. As seen inFIG. 13, a leading_acks field 188 and a following_acks_field 190 arecounts of the number of DATA frames 106 actually received(state=“ready”) in the inbound queue 135 that reside immediately priorto and immediately after the DATA frame 106 being ACK'd, causing ACKframes 110 to “overlap” each other.

The leading_acks field 188 and the following_acks_field 190, togetherwith the at_top field 186, allow a receiver of the ACK frame 110 todeduce information about which of its DATA frames 106 have actually beenreceived on the other end. The receiver of an ACK frame 110 does not usethe overlap information to send a RETRY frame 114 or WINDOW frame 116,or to reset a timer waiting for a still pending ACK 110. The correctresponse is simply to use the information as supplemental ACK's andremove corresponding DATA frames 106 from the outbound queue 131.

The counting of contiguous DATA frames 106 that have actually beenreceived is not a significant burden on the device 12, since the inboundqueue 135 is usually small.

ACK Frame seqnum Field.

The sequence number 112 of the ACK frame 110 is set to the sequencenumber 108 of the DATA frame 106 being ACK'd.

ACK Frame at_top.

The at_top field 186 is set to true if there are no “missing” DATAframes 106 in the inbound queue 131 prior to the DATA frame 106 beingACK'd. Sometimes the leading_acks field 188 may not be large enough tocount all the received DATA frames 106 prior to the DATA frame 106 beingACK'd. However, this condition does not affect the value of the at_topfield 186. If the DATA frame 106 being ACK'd is the very first frame 106in the inbound queue 131, at_top 186 is set to true.

ACK Frame leading_acks.

The leading_acks field 188 can hold a value in the range 0.127. If thereare more than 127 “ready” DATA frames 106 in the inbound queueimmediately (and contiguously) prior to the DATA frame 106 being ACK'd,the leading_acks field 188 simply holds a value of {127}.

ACK Frame following_acks.

The following_acks field 198 can hold a value in the range 0 . . . 255.If there are more than 255 “ready” DATA frames 106 in the inbound queue135 immediately (and contiguously) following the DATA frame 106 beingACK'd, the following_acks field 190 simply holds a value of {255}.

ACK Frame Validation Check.

An ACK frame 110 is typically a specific size, such that the receipt ofan ACK frame 110 having a size different than that specified indicates anon-valid ACK frame 110. For example, in a current embodiment of theWireless datagram transaction protocol system 100, a valid ACK frame hasexactly 6 bytes.

Retry Frames.

FIG. 14 is a schematic view of a RETRY frame 114, comprising a CRC 201,a First Sequence Number in Inbound Queue 202, a MISS 1 204, and ACK 1206; a MISS 2 208, and ACK 2 210; a MISS 3 212, and ACK 3, 214; a MISS 4216, and an ACK 4 218, as shown:

<crc><0100:seqnum><miss1><ack1><miss2><ack2><miss3><ack3><miss4><ack4>  (9)

A RETRY frame 114 specifies the sequence numbers 108 of DATA frames 106that need to be resent, and also indicates which DATA frames 106 havealready been received. A RETRY frame therefore provides a picture to arecipient of the state of the sender's inbound queue 135. The relativesizes of exemplary RETRY frame 114 elements are shown in Table 8.

TABLE 8 crc  2 bytes CRC of the frame seqnum 12 bits the sequence numberthat begins the run miss1  1 byte count of missing DATA frames startingwith seqnum ack1  1 byte count of received DATA frames following miss1miss2  1 byte count of missing DATA frames following ack1 ack2  1 bytecount of received DATA frames following miss2 miss3  1 byte count ofmissing DATA frames following ack2 ack3  1 byte count of received DATAframes following miss3 miss4  1 byte count of missing DATA framesfollowing ack3 ack4  1 byte count of received DATA frames followingmiss4

A receiver of DATA frames 106 can decide whether one or more DATA frames106 missing, by keeping track of sequence numbers 108, as DATA frames106 arrive, and by detecting gaps in the series of sequence numbers 108.

Retry Frame Server Retry Logic.

The wireless datagram protocol system 100 comprises retry logic which isasymmetric between a server 14 and a device 12, which minimizes thetransmissions required from the wireless device 12. Since transmitting38 consumes more battery power 54,56 than receiving 40, the asymmetricretry logic conserves available battery power for the wireless device12.

The server 14 sends a RETRY frame 114 to the device 12 for two reasons.In a first RETRY condition, the server 14 sends a RETRY frame 114 to thedevice 12 if the server receives a WINDOW frame 116 from the Device 12.In a second RETRY condition, the server 14 sends a RETRY frame 114 tothe device 12 if the server ‘times out’ waiting for a missing DATA frame106 from the device 12.

In the first retry condition, when the server 14 receives a WINDOW frame116 from the device 12, the server 14 responds by sending one or morefully specified RETRY frames to the Device, wherein a “Fully specified”RETRY frame 114 includes filling in all the missX 204,208,212,216 andackX fields 206,210,214,218. The intent of the fully specified RETRYframe 114 is to inform the device 12 of all DATA frames 106 whose stateis “missing”, regardless of how long the data frames 106 have beenmissing.

In the second retry condition, wherein the server 14 sends a RETRY frame114 as a result of timing out while waiting for a missing DATA frame106, the sent RETRY frame 114 is not necessarily “fully specified.” Inthe second retry condition, the server 14 sends one or more RETRY frames114 to the device 12, specifying only those DATA frames 114 that havebeen missing for at least N seconds, wherein N is preferably hostconfigurable. A specified time greater than or equal to N helps to avoidasking the device 12 to resend a DATA frame 106 that is already inflight to the server 14. The server 14 typically checks for overdue DATAframes 106 in a periodic manner, e.g. every M seconds, wherein theperiod M is preferably host configurable.

The device 12 properly responds to a RETRY frame 114 by immediatelyresending outbound DATA frames 106 that are in the ‘missing’ ranges, andby removing DATA frames 106 from the outbound queue 131 that are in the‘ack’ ranges. Care is taken when removing DATA frames 106 from theoutbound queue 131, since some DATA frames may have already been removedas a result of a previous ACK frame 110.

Retry Frame Device Retry Logic.

The device 12 only sends RETRY frames 114 to the server 14 in responseto receiving a WINDOW frame 116. This way the device 12 doesn'tcontinually send RETRY frames 114 until the server 12 finally receivesone.

Upon receipt of a RETRY frame 114 from a device 12, the server 12responds by immediately resending outbound DATA frames 106 that are inthe ‘missing’ ranges, and by removing DATA frames 106 from the outboundqueue 135 that are in the ‘ack’ ranges. Care is taken when removing DATAframes 106 from the outbound queue 131 of the server 14, since some DATAframes 106 may have already been removed as a result of a previous ACKframe 110.

Retry Frame Format.

The format of the RETRY frame 114 specifies a starting sequence number202 followed by a plurality of, e.g. eight, run lengths 202-218. In FIG.14, the eight run lengths indicate the number of DATA frames 106 thatare: missing 204, received 206, missing 208, received 210, missing 212,received 214, missing 216, and received 218. In one exemplary embodimentof the Wireless datagram transaction protocol system 100, wherein runlengths are 1-byte values, and wherein only eight runs may be specified,a single RETRY frame 114 may be insufficient to specify the state of theentire inbound queue 135, wherein an inbound queue may be as large as1024 frames. Therefore, multiple RETRY frames 114 may be required tofully specify the state of the entire inbound queue 135.

In a typical embodiment of the Wireless datagram transaction protocolsystem 100, missing DATA frames 106 are generally clumped together. Theplurality of runs 204-218 within a REPLY frame 114 reduces the number ofRETRY frames 114 required to fully specify the state of the entireinbound queue 135. While eight runs are specified in one embodiment ofthe Wireless datagram transaction protocol system 10, the number of runs204-218 may alternatively be tuned to a different number, such as basedupon practice, to minimize the overhead required to recover from packetloss.

Retry Frame seqnum Field.

The seqnum field 202 of a RETRY frame 114 contains the sequence numberof the first frame in the inbound queue 135.

Retry Frame MISS fields and ACK Fields.

The miss1 field 204 is the count of how many DATA frames 106 aremissing, beginning with seqnum 202. The ack1 field 206 is the count ofhow many DATA frames 106 have been received following the run of missingDATA frames 106 specified by miss1 204. Similarly, miss2 208, ack2 210,miss3 212, ack3 214, miss4 216, and ack4 218 fields comprise the countof how many DATA frames 106 are in alternating runs of missing andreceived DATA frames 106 following the ack1 run 206. Some examples forunusual cases are presented, as shown:

Retry Frame Example A

The inbound queue 135 starts with five frames 106 ready to be processed,then 3 missing frames. The first frame has a sequence number=14:

<crc><RETRY:14><0><5><3><0><0><0><0><0>  (10)

Retry Frame Example B

The inbound queue 135 is empty, next_seqnum_in=103:

<crc><RETRY:103><0><0><0><0><0><0><0><0>

Retry Frame Example C

The inbound queue 135 has 500 missing frames 106, followed by 300 framesready for processing. The first frame has a sequence number=951:

<crc><RETRY:951><255><0><245><255><0><45><0><0>  (12)

Retry Frame Example D

The inbound queue 135 has 11 frames, alternating missing and ready everyother frame. The first frame has a sequence number=20:

<crc><RETRY:20><1><1><1><1><1><1><1><1>

≧crc><RETRY:28><1><1><1><0><0><0><0><0>  (13)

Retry Frame Validation Check.

A RETRY frame 114 is typically a specific size, such that the receipt ofa RETRY frame 114 having a size different than that specified indicatesa non-valid RETRY frame 114. For example, in a current embodiment of theWireless datagram transaction protocol system 100, a valid RETRY framehas exactly 12 bytes.

Window Frames.

FIG. 15 is a schematic view 220 of a WINDOW frame 116, comprising awindow frame CRC 222, and a window frame seqnum 224, as shown:

<crc><0101:seqnum>  (14)

In current embodiments of the Wireless datagram transaction protocolsystem 100, a WINDOW frame 116 is only sent when there is a suspicionthat a DATA frame 106 has not been received. The receiver, e.g. a device12 or server 14, of a WINDOW frame 116 has enough information to computethe window from the perspective of the sender (more accurately, what thesender would like the window to be). The receiver responds to a WINDOWframe 116 by sending one or more RETRY frames 114 to get the window backin sync. The relative sizes of exemplary WINDOW frame 116 elements areshown in Table 9.

TABLE 9 crc  2 bytes CRC of the frame seqnum 12 bits the next_seqnum_outvalue

The logic for sending a WINDOW frame 116 is asymmetric between theserver 14 and the device 12, thereby minimizing the transmissionsrequired from the wireless device 12. Since the transmission of aforward link signal 38 consumes more battery power 56 than the receiptof a reverse link signal 40, the asymmetric WINDOW frame logic serves tominimize battery consumption for a device 12 having limited powerresources 54,56.

Window Frame Server Logic.

The server 14 sends a WINDOW frame 116 if any DATA frame 106 the server14 has sent is not ACK'd within a specified time period, e.g. N seconds.The server 14 typically checks periodically for overdue ACK's, e.g.every M seconds.

Window Frame Device Logic.

The device 12 sends a WINDOW frame 116 only when it has timed outwaiting for the window 254 to open. The device 12 must start a timer 281when the device 12 attempts to send a DATA frame 106, but isunsuccessful on a condition when the window is closed. Events which areused to clear the window-closed timer are

-   -   receiving an ACK (or overlapping ACK) frame 110 for the very        first DATA frame 106 in the outbound queue 131; or    -   receiving a RETRY frame 114 that allows the device 12 to        implicitly ACK the very first DATA frame 106 in the outbound        queue 131.

When the device 12 sends the WINDOW frame 116, the device 12 restartsthe timer 281.

The device 12 relies on the server 14 to send RETRY frames 114 for DATAframes 106 which the server 14 is missing. However, the server 14 has noway of knowing if the last DATA frame 106 sent by the device 12 neverarrived. If the DATA frames 106 on the end of the device outbound queue131 stack up, the window 254 may become closed, which is detectable onlyby the device 12.

Window Frame seqnum Field.

The seqnum field contains sequence number of the sender's first outboundDATA frame whose state is “waitingForWindow”, if there is one.Otherwise, this field contains the current value of the sender'snext_seqnum_out field.

Window Frame Validation Check.

As described above for other WDTP frames 101, a WINDOW frame 116 istypically a specific size, such that the receipt of an WINDOW frame 116having a size different than that specified indicates a non-valid WINDOWframe 116. For example, in a current embodiment of the Wireless datagramtransaction protocol system 100, a valid WINDOW frame 116 has exactly 4bytes.

RESET Frames.

FIG. 16 is a detailed schematic view of a RESET frame 118, whichcomprises a reset CRC 228, and a reset key 230, which is comprised of areset key A 232 and a rest key B 234, as shown:

<crc><0110:reset_key_a><reset_key_b>  (15)

The RESET frame 118 instructs the server 14 to reset its WDTP Manager862 (FIG. 46), i.e. to purge all the queues 131,135, and return to theeWDTP_stopped state 492 (FIG. 30), whereby the server 14 will then beready to receive an INIT frame 102 from the device 12. The relativesizes of exemplary RESET frame 118 elements are shown in Table 10.

TABLE 10 crc  2 bytes CRC of the frame reset_key_a 12 bits part of first2 bytes of the reset key reset_key_b  2 bytes last 2 bytes of the resetkey

Whenever the server 14 receives a RESET frame 118 from the device, theserver 14 replies with an identical RESET frame 118, after verifying theauthenticity of the Reset Key 230. The device 12, upon receipt ofreplying RESET frame 118 from the server, may then begin the INITsequence.

In current embodiments of the Wireless datagram transaction protocolsystem 100, the server 14 never initiates the reset handshake.Therefore, the device 12 ignores a RESET frame 118, unless its WDTPstate is eWDTP_waitingForReset, which is the state of the device 12 uponinitiating a reset handshake, i.e. sending a RESET frame 118 to theserver 14.

Reset Frame Reset Key.

The reset frame reset key 230 shown in FIG. 16 comprises a 3½ byte (28bit) value that is initially computed by the device 12, and istransmitted to the server 12 in the READY frame 104. The reset_key_afield 232 holds the first 12 bits of the Reset Key 230. The reset_key_bfield 234 holds the last 2 bytes of the Reset Key 230.

The purpose of the reset key 230 is to verify that the sender of a RESETframe 118 is actually the owner of the WDTP connection. When the server14 receives a RESET frame 118, the server 14 compares the reset key 230to the reset key 166 the server 14 received in the READY frame 104during initialization. If the keys 230,166 don't match, the server 14simply ignores the frame 118.

Reset Frame Validation Check.

As described above for other WDTP frames 101, a RESET frame 118 istypically a specific size, such that the receipt of a RESET frame 118having a size different than that specified size indicates a non-validRESET frame 118. For example, in a current embodiment of the Wirelessdatagram transaction protocol system 100, a valid RESET frame 118comprises exactly 6 bytes.

ERROR Frames.

FIG. 17 is a detailed schematic view 236 of an ERROR frame 120,comprising an error frame CRC 238, an error frame sequence number(seqnum) 240, and an error frame error code 242, as shown:

<crc><0111:seqnum><errcode>  (16)

The relative sizes of exemplary ERROR frame 120 elements are shown inTable 11.

TABLE 11 crc  2 bytes CRC of the frame seqnum 12 bits set to010101010101 (0x0555) for validation errcode  2 bytes the error code

In current embodiments of the Wireless datagram transaction protocolsystem 100, only the server 14 sends ERROR frames 120. The purpose of anERROR frame 120 is to inform the device 12 that a severe protocol errorhas occurred. The response to an ERROR frame 120 from a device 12depends on the error code 242. The seqnum field 240 is used to validatethe ERROR frame 120, and is typically set to a value which signifies anerror condition, e.g. such as a value 0×0555. The error code (errcode)field 242 contains the numeric value of the error code being returned,as shown in Table 12. Detailed examples of process flows with errors andrecovery are described below.

TABLE 12 Error code Error Device response 1 Unexpected_frame_while Ifthe Device's WDTP state is _Running eWDTP_waitingForinit, the devicemust perform a RESET handshake with the Server and then restart the initsequence. Otherwise, the device can ignore this error. 2Unexpected_frame_while Device resets its WDTP Manager _Stopped andbegins init sequence.

Error Frame Validation Check.

As described above for other WDTP frames 101, an ERROR frame 120 istypically a specific size, such that the receipt of an ERROR frame 120having a size different than that specified size indicates a non-validERROR frame 120. For example, in a current embodiment of the Wirelessdatagram transaction protocol system 100, a valid ERROR frame 120comprises exactly 6 bytes. Similarly, the value of a seqnum field 120signifies an error condition, e.g. having a value other than 0×0555. Aswell, a valid errcode field 242 must have a valid error value, such as avalue in the set {1, 2}, as shown in Table 12.

WDTP Manager and WDTP States.

The application management of WDTP transactions, is typically handledthrough a WDTP Manager class, that contains the inbound and outboundqueues and the current WDTP state. The WDTP Manager typically includes areference (or singleton access) to the datagram interface object, asshown in Table 13. During initialization of the object WDTP Managerconstructor must initialize_state to eWDTP_stopped.

TABLE 13 enum WDTPState { eWDTP_stopped, eWDTP_waitingForInit,eWDTP_waitingForReady, eWDTP_waitingForReset, eWDTP_running }; classWDTPManager { public: // methods ... private: // members WDTPState_state; // state of WDTP WDTPqueue_inbound; // queue of inbound DATAframes WDTPqueue_outbound; // queue of outbound DATA frames UDP& _udp;// datagram interface object };

Sequence Numbers and DATA Frame States. When an application has data 180to send, it creates a DATA frame 106 that is appended to the outboundqueue 131.

Before the DATA frame 106 is actually transmitted, the window 254 (FIG.18) is checked to make sure it is open.

The receiver, e.g. either the device 12 or server 14, similarly performschecking to validate an inbound DATA frame 106. The ‘window’ 254 iscomprised of a continuous range of valid sequence numbers, wherein:

window={first_valid_seqnum . . . lastvalid_seqnum}.  (17)

If the sequence number 108 of a DATA frame 106 lies within the window,i.e. the ‘window is open’, then the DATA frame 106 may be transmitted ina datagram 19.

In the algorithms presented below, the outbound window computed by thesender is a subset of the validation (inbound) window computed by thereceiver. The outbound window is a subset, and often an identical set ofthe validation window, because the sender never shifts its outboundwindow until it receives an ACK 110 for the first sequence number in theoutbound window.

DATA Frame States.

The application maintains the state of each DATA frame 106 that is inthe outbound queue 131, to keep track of whether a DATA frame has beensent. As soon as a DATA frame 106 is ACK'd 110, the DATA frame 106 canbe removed from the outbound queue 131. Table 14 provides a summary ofDATA is frame states.

TABLE 14 Outbound state Definition waitingForWindow initial state of aDATA frame; not yet sent in a datagram sent DATA frame has beentransmitted in a datagram; now waiting for an ACK Inbound stateDefinition missing placeholder for a DATA frame that has not yet arrivedready DATA frame has been received and is now waiting for theapplication to process it

Procedure to Determine Whether the Window is Open to Send a DATA Frame.

The sender of a DATA frame 106 must determine whether the window is openbefore actually transmitting it in a datagram 19. The receiver assumesthat the sender does this check. The receiver uses that assumption aspart of the sequence number validation when a DATA frame 106 isreceived.

FIG. 18 is a flowchart of a basic process 250 for determining whether awindow is open to send a DATA frame 106. The window 254 is firstdetermined 252, and then the computed window 254 is checked 256 to seeif the window 254 is open for the DATA frame 106. If the window 254 isopen, the DATA frame is sent 258.

FIG. 19 is a detailed flowchart of a process 252 for computing a window254 in the Wireless datagram transaction protocol system 100. The stateof the outbound queue 131 is determined 260. If the outbound queue 131is empty 264, the first valid sequence number is equal to thenext_seqnum_out 266. If the outbound queue 131 is not empty 268, thereis a data frame 106 in the queue, such that the first_valid_seqnum isset to equal the outbound_queue<0>.seqnum 270. Once the first validsequence number is determined 266,270, the out_window equals the seqnumrange, beginning with the first_valid_seqnum, and containingoutwindow_size contiguous elements, i.e. the window contains a pluralityof contiguous elements, wherein the number of the plurality isdetermined by the outwindow_size.

FIG. 20 is a detailed flowchart of a process 256 for checking to see ifa window is open to send a DATA frame 106. A determination is performed274 to see if the out_window contains DATA.seqnum. A positive result 276indicates that the window is open, whereby the DATA frame 106 is sent258. If the window is closed 278, it is then determined 280 whether thetimer 281 is on. In one embodiment 256, upon a positive result 286, itis then determined if the timer has timed out 288. If the timer hastimed out 290, a WINDOW frame 116 is sent 300. If the timer has nottimed out 302, the process returns. As well, if the timer 281 is not on282 at step 280, the timer is started 284. In an alternate embodiment ofthe wireless datagram transaction protocol system 100, the timeout check303 is provided in a separate process.

Validation for Inbound DATA Frame Sequence Numbers.

FIG. 21 is a flowchart 304 showing validation for inbound DATA Framesequence numbers 108. When a DATA frame 106 is received, its sequencenumber 108 is validated before the DATA frame 106 is accepted. Aninvalid sequence number 108 implies corruption, since the receiver knowsthat the sender is checking for an open window before transmitting. DATAframes 106 with an invalid sequence number 108 are therefore discarded.

The window is first computed 306, wherein in_window is equal to thesequence number range defined by the next sequence number in, and thesize of the in window. It is then determined 307 if the window is opento receive a given data frame 106, wherein it is determined if thein_window contains DATA.seqnum, at 308.

If the determination 308 is positive 310, the DATA frame 106 isprocessed 312, and the recipient replies 314 with an ACK frame 110. Ifthe determination 308 is negative 316, i.e. the sequence number is bad316, the DATA frame 106 is discarded 318.

Rules for Updating next_seqnum_in and next_seqnum_out.

Updating next_seqnum_in.

FIG. 22 is a flowchart showing rules 320 for updating the next sequencenumber in. The next_seqnum_in variable should always indicate the nextexpected DATA frame in the inbound sequence, even though DATA frameswith higher sequence numbers may have been received out of order.

Upon receipt 322 of a DATA frame 106 with a valid sequence number 108,the DATA frame is inserted 324 into the inbound queue 135 (FIG. 8). Itis then determined if the DATA frame 106 and associated seqnum 108 areequal to the next_seqnum_in, at step 326.

If the determination 326 is positive 328, the window is shifted 330, tobegin with the first “missing” DATA frame 106. If it is determined 332that the inbound queue 135 does not 334 have missing frames 106, all theframes are ready, then set n equal to inbound_queue.lastFrameIndex( )336, then next_seqnum_in=inbound_queue<n>.seqnum 338, and the processcontinues to next_seqnum_in++340. If it is determined 332 that theinbound queue 135 does 342 have missing frames 106,n=inbound_firstMissingFrameIndex( ) 344, andnext_seqnum_in=inbound_queue<n>.seqnum 346. The algorithm for thisprocess is seen in Table 15.

TABLE 15 receive DATA frame with valid sequence number insert DATA frameinto inbound_queue if ( DATA.seqnum == next_seqnum_in ) { if (inbound_queue.hasMissingFrames( ) ) { // shift the window so that itbegins with the 1^(st) ‘missing’ frame n =inbound_queue.firstMissingFrameIndex( ); next_seqnum_in =inbound_queue<n>.seqnum } else // all frames are ‘ready’ { // shift thewindow so that it starts after the last ‘ready’ frame n =inbound_queue.lastFrameIndex( ); next_seqnum_in =inbound_queue<n>.seqnum; next_seqnum_in++; } }

Updating next_seqnum_out.

The next_seqnum_out variable indicates the sequence number 108 of thenext DATA frame 106 that will be added to the outbound queue 131. Thenext_seqnum_out variable is incremented each time a new DATA frame isadded to the outbound queue 131.

Class for Handling Wrapping Sequence Numbers.

In some embodiments of the wireless datagram transaction protocol system100, sequence numbers, such as associated sequence number 108 and ACKsequence numbers 112, may be contained in an object and manipulatedthrough class functions that accommodate the wrapping property, as shownin Table 16. FIG. 23 is a diagram 352 showing a class for handlingwrapping sequence numbers.

TABLE 16 class WDTP_seqnum { public: // methods WDTP_seqnum( UInt16seqnum ) : _seqnum( seqnum ) { } WDTP_seqnum& operator += ( UInt16 value); WDTP_seqnum& operator ++ ( ); // prefix increment UInt16 Value( )const { return _seqnum; } private: // members UInt16_seqnum; };

FIG. 24 and FIG. 25 show an implementation of operator methods 372, 380for wireless datagram transaction protocol (WDTP) sequence numbers. Analgorithm for the implementation of the operator methods for WDTP seqnumis shown in Table 17.

TABLE 17 WDTP_seqnum& WDTP_seqnum::operator += ( UInt16 value ) { UInt32temp = _seqnum; _seqnum = (temp + value) % 4096; return *this; }WDTP_seqnum& WDTP_seqnum::operator ++ ( ) { if ( _seqnum == 4095 ) //4095 is the max value of a sequence number { _seqnum = 0; // wrap aroundto zero } else { _seqnum++; } return *this; }

Class for Handling Windows of Sequence Numbers.

In a typical embodiment of the wireless datagram transaction protocolsystem 100, as seen in FIG. 8, the value of sequence numbers 108 canwrap. Therefore, a window of values can possibly fall into two ranges.For example, a window with a size of 10 that starts with the sequencenumber 4090 would contain the following values:

-   -   window(4090, 10)={4090, 4091, 4092, 4093, 4094, 4095, 0, 1, 2,        3}

That set of values is comprised of two disjoint subsets:

-   -   {4090, 4091, 4092, 4093, 4094, 4095} and {0, 1, 2, 3}

In a wireless datagram transaction protocol system 100 that limits thewindow size to 1024 frames, which is smaller than the range of possiblesequence numbers, a window cannot wrap more than once. Therefore, it isonly necessary for a window to support at most two disjoint subsets.

A method for encapsulation of window behavior within a class is seen inTable 18. FIG. 26 is a diagram 394 illustrating the associatedprocessing of windows comprising sequence numbers, as shown in Table 18.

TABLE 18 class WDTP_window { public: // methods WDTP_window( UInt16seqnum, UInt16 windowSize ); bool Contains( UInt16 seqnum, bool&liesWithinWrappedRange ) const; private: // members UInt16 _x0; // startof 1st range UInt16 _x1; // end of 1st range UInt16 _x2; // start of 2ndrange UInt16 _x3; // end of 2nd range };

In practice, the WDTP_window class is typically processed as shown:

TABLE 19 WDTP_window in_window( next_seqnum_in, in_window_size ); boolliesWithinWrappedRange; if ( in_window.Contains( DATA.seqnum,liesWithinWrappedRange ) ) { // Process DATA frame }

Construction of WDTP Window.

FIG. 27 is a flowchart showing the process 412 of constructing awireless datagram transaction protocol (WDTP) window, having analgorithm seen in Table 20.

TABLE 20 WDTP_window:: WDTP_window( UInt16 seqnum, UInt16 windowSize ) {// initialize the 1st range so it's empty _x0 = 1; _x1 = 0; //initialize the 2nd range so it's empty _x2 = 1; _x3 = 0; if (windowSize > 0 ) { // find the value of the last element in the windowWDTP_seqnum last( seqnum ); last += (windowSize − 1); // set the ranges_x0 = seqnum; if ( last.Value( ) >= seqnum ) { _x1 = last.Value( ); }else // it wrapped { _x1 = 4095; _x2 = 0; _x3 = last.Value( ); } } }

Table 21 provides an algorithm showing a Contains( )method forWDTP_window.

TABLE 21 bool WDTP_window::Contains( UInt16 seqnum, bool&liesWithinWrappedRange ) const { liesWithinWrappedRange = false; if (_x0 <= seqnum && seqnum <= _x1 ) { return true; } if ( _x2 <= seqnum &&seqnum <= _x3 ) { liesWithinWrappedRange = true; return true; } returnfalse; }

WDTP System Timeouts.

FIG. 28 is a schematic diagram of server timeout rules 460 in thewireless datagram transaction protocol system 100. The server 14 and thedevice 12 are each responsible for timing out certain transactions.While basic embodiments of the wireless datagram transaction protocolsystem 100 do not use adaptive timeouts, alternate embodiments of thewireless datagram transaction protocol system 100 are able to adjusttimeouts, based on perceived network speed. The following server rulesare implemented in some embodiments of the wireless datagram transactionprotocol system 100.

-   -   The server checks for overdue ACK frames every M seconds.    -   The server checks for overdue DATA frames every N seconds.    -   An ACK frame 110 is overdue at the server 14 if it is not        received within P seconds.    -   A DATA frame 106 is overdue at the server 14 if it is not        received within Q seconds.    -   M, N, P, and Q are all host configurable.

FIG. 29 is a schematic diagram of device timeout rules 470 in thewireless datagram transaction protocol system 100. The following serverrules are implemented in some embodiments of the wireless datagramtransaction protocol system 100.

-   -   The device 12 uses a timer that can activate the application if        it is dormant.    -   Events that should clear the window-closed timer are typically        limited to:        -   receiving an ACK (or overlapping ACK) frame for the very            first DATA frame in the outbound queue        -   receiving a RETRY frame that allows the device to implicitly            ACK the very first DATA frame in the outbound queue

Examples of Process Flows with No Errors.

FIG. 30 and FIG. 31 show process flow 490 a,490 b in the wirelessdatagram transaction protocol system 100 with no errors. FIG. 32 shows aprocess 520 for sending DATA frames from a device 12 to a server 14.FIG. 33 shows a detailed process 550 for sending acknowledgement ACKframes from a server 14 and a device 12. When there are no errors, thescenarios shown in FIG. 32 and FIG. 33 are identical for the server 14sending a DATA frame 106, and the device 12 replying with an ACK frame110.

Error Scenarios and Processes.

The wireless datagram protocol system 100 provides comprehensive controlfor error scenarios and responses. FIG. 34 is an overview chart 570which shows error categories and associated process flows within awireless datagram transaction protocol (WDTP) system 100.

Error Scenarios.

FIG. 35 is a chart 600 which shows error scenarios and responses forlost INIT Frames and READY Frames. FIG. 36 is a chart 620 which showserror scenarios and responses for lost DATA Frames. FIG. 37 is a chart640 which shows error scenarios and responses for lost ACK Frames. FIG.38 is a chart 660 which shows error scenarios and responses for a lostRETRY Frame. FIG. 39 is a chart 680 which shows error scenarios andresponses for a lost WINDOW Frame. FIG. 40 is a chart 700 which showserror scenarios and responses for a lost RESET Frame. FIG. 41 is a chart720 which shows an error scenario and response for a lost ERROR Frame.FIG. 42 is a chart 760 which shows error scenarios and responses for aduplicate Frame received. FIG. 43 is a chart 780 which shows errorscenarios and responses to the arrival of a bogus frame having a validheader. FIG. 44 is a chart 800 which shows error scenarios and responsesfor a Frame received with an invalid frame type. FIG. 45 is a chart 820which shows error scenarios and responses for a Frame received with anInvalid sequence number. FIG. 46 is a chart 860 which shows errorscenarios and responses for a DATA Frame which is received before anINIT Frame. FIG. 47 is a chart 900 which shows error scenarios andresponses for an INIT Frame which is received after a DATA Frame.

Sample Process Flows with Errors and Recovery.

The wireless datagram protocol system 100 provides an integrated set ofprocess responses to error conditions. Some exemplary process responsesare shown in Table 22.

TABLE 22 1. Init sequence with timeouts 2. DATA, ACK, WINDOW, and RETRYinteraction with timeouts  a. Device 12 sends 2 DATA frames, the firstnever arrives  b. Device 12 sends 3 DATA frames; number 1 and 2 neverarrive,   the window is closed for number 3  c. Server 14 sends 2 DATAframes, the first never arrives  d. Device 12 sends 1 ACK frame, itnever arrives 3. Responding to ERROR - Unexpected_frame_while_Running 4.Responding to ERROR - Unexpectedframe_while_Stopped

In the detailed flows shown in FIG. 48 to FIG. 56, the frames areenclosed within [ ]'s. Only the relevant parts of the frame are shown.For example, DATA frames are displayed as [DATA:nnn] where ‘nnn’ is thesequence number, but the actual data is not shown.

FIG. 48 and FIG. 49 show wireless datagram transaction protocol system100 process flow 940 a,940 b through an Init sequence with timeouts.FIG. 50 shows beginning device 12 and server 14 states 970 for DATA,ACK, WINDOW, and RETRY processes. FIG. 51 shows exemplary stateinteractions 990 between a device 12 and a server 14, when the device 12sends two DATA Frames 106, and the first frame 106 never arrives at theserver 14. FIG. 52 shows exemplary state interactions 1000 between adevice 12 and a server 14, when the device 12 sends three DATA Frames106, wherein the first and second DATA frames 106 never arrive at theserver 14, and wherein the WINDOW is closed for the third DATA frame106. FIG. 53 shows exemplary state interactions 1040 between a device 12and a server 14, when the server 14 sends two DATA frames 106, and thefirst DATA frame 106 never arrives at the device 12. FIG. 54 showsexemplary state interactions 1080 between a device 12 and a server 14,when the device 12 sends an ACK Frame 110, which never arrives at theserver 14. FIG. 55 shows exemplary state interactions 1120 between adevice 12 and a server 14, when the server 14 receives an unexpectedINIT frame 102 while in the Running state. FIG. 56 shows exemplary stateinteractions 1160 between a device 12 and a server 14, when the server14 receives an unexpected DATA frame 106 while in the Stopped state.

Although the wireless datagram transaction protocol system 100 and itsmethods of use are described herein in connection with wireless devices,personal computers and other microprocessor-based devices, such aswireless appliances, the apparatus and techniques can be implemented fora wide variety of electronic devices and systems, or any combinationthereof, as desired.

Furthermore, while the wireless datagram transaction protocol system 100and its methods of use are described herein in connection with wirelessdevices and intranets or LAN's, the apparatus and techniques can beimplemented for a wide variety of electronic devices and networks or anycombination thereof, as desired.

As well, while the wireless datagram transaction protocol system 100 andits methods of use are described herein in connection with a time basedinteraction between a wireless device and a server, the wirelessdatagram transaction protocol can be implemented for a wide variety ofelectronic devices and networks or any combination thereof, as desired.

Accordingly, although the invention has been described in detail withreference to a particular preferred embodiment, persons possessingordinary skill in the art to which this invention pertains willappreciate that various modifications and enhancements may be madewithout departing from the spirit and scope of the claims that follow.

1. A device, comprising: a receiver for receiving a sequence of DATAframes from a second device; a transmitter for sending wireless signalstoward the second device; a processor programmed to provide anacknowledgement frame to the transmitter for transmission toward thesecond device, the acknowledgement frame 10 associated with a DATA frameof the sequence of DATA frames that is received from the second device,the acknowledgment frame comprising an acknowledgement sequence numberthat refers to the received DATA frame of the sequence of DATA frames,the received DATA frame having an associated sequence number thatmatches the acknowledgement sequence number, and a count of contiguousDATA frames within the sequence of DATA frames that have been receivedat the device, wherein the count overlaps the DATA frame having anassociated sequence number that matches the acknowledgement sequencenumber; wherein the acknowledgment frame implies receipt at the deviceof the DATA frame having an associated sequence number that matches theacknowledgement sequence number, and at least one other DATA framewithin the sequence of DATA frames that corresponds to the count ofcontiguous DATA frames. 2-22. (canceled)